Protecting metal storage tanks from corrosive materials such as acid has historically required the application of rubber sheeting to the tank walls. However, to bond the rubber to the walls, adhesives containing volatile organic solvents are typically employed. Such adhesives typically contain volatile organic solvents, such as, for example toluene, methyl chloride, xylene and the like. Moreover, the application of the adhesive is tedious; multiple coatings are typically required. Typically, both the metal wall and the rubber sheeting are solvent washed and both are coated with adhesive.
Seaming the rubber sheeting while lining a tank also presents problems. The seaming process typically requires the application of volatile organic solvents and cements that contain volatile organic solvents. Moreover, seaming cement are often susceptible to attack by the tank contents.
In addition to environmental concerns, the presence of the organic solvents in the wash and the cement in the enclosed tank necessitate extreme care in handling of equipment to prevent the generation of a spark. Explosion proof lighting must be employed. The enclosed tank also requires that special respiratory protection be employed.
In an attempt to eliminate some of the volatile organic solvents, water based systems have been employed to adhere the rubber sheeting to tank walls. However, such water based systems have proved unsatisfactory; they fail to bond the rubber sheeting to the metal walls particularly when exhaust steam cured. Moreover, the water in the system rusts the metal walls of the tank.
It would be desirable to have a method of protecting metal tank walls from corrosive materials that do not employ volatile organic compounds.
The invention relates to a novel composite liner which preferably does not employ volatile organic compounds. The composite liner comprises a chemical resistant layer, and a tie layer which is tacky prior to cure, disposed on the chemical resistant layer. Once the tie gum layer is disposed on the substrate such as a tank liner wall, and cured, the composite liner adheres tightly to the substrate. The invention also relates to a novel tie gum composition useful for the tie layer, which comprises a rubber system and an additive system. The rubber system comprises a halogenated, sulfonated polyolefin, and an epoxidized elastomer, and preferably a low viscosity halogenated rubber. The additive system comprises a curing agent for the epoxidized rubber, preferably an acid acceptor for the halogenated, sulfonated polyolefin, preferably a tackifier, and preferably an adhesion agent. Preferably the tie gum does not employ volatile organic compounds.
The invention further relates to a novel method of sealing the seams of composite liner, using a terpene seaming composition or a water based elastomeric seaming composition. The invention also relates to a novel epoxy primer comprised of an epoxy resin system comprising: a liquid bisphenol A epichlorohydrin epoxy resin, having at least two epoxy groups per molecule and an elastomer modified epoxy resin; and primer additives comprising a liquid epoxy functional modifier, and a curing agent in an amount effective to cure the epoxy resin system.
The present invention relates to novel methods of applying composite liners to substrates, particularly metal tanks. The method of applying the composite liner to a substrate preferably does not employ volatile organic compounds. The method comprises the following steps: applying an epoxy primer to the substrate; and then applying the composite liner to the substrate. Preferably the composite liner is seamed by applying a seaming composition to the edges of the composite liner and preferably stitching the composite liner panels together.
The invention also relates to lined substrates that is substrates particularly tanks, which have the composite liner adhered thereto.